1. Field of Invention
The present invention relates to a metallic photonic box and its manufacturing processes, and more particularly to a metallic photonic box that improves the illumination efficiency of light radiation at a certain range of wavelength.
2. Description of Related Arts
Since 1879 when Thomas Edison invented the incandescent light, many efforts have been directed to its improvement of illumination efficiency, energy saving and cost of manufacturing. Given that more than 30 percent of electric power generated worldwide is used in lighting, an illumination apparatus having better illumination efficiency and saving more energy is much needed. This is particularly true when natural resources for generating electricity are exhausting rapidly in today's age.
An incandescent light, as one of the most frequently used illumination apparatuses, includes a tungsten filament having electric current running therethrough for heating to about 2,200 degrees Celsius, thereby generating light radiation. However, it has the shortcomings, such as fragile, less efficient, energy wasting and short living.
Due to the development of technology, fluorescent lights and light emitting diodes (LED) have been invented for better light sources.
Fluorescent Light
A fluorescent light is composed of an air-tight gas discharge tube with its two ends respectively attached with filaments coated with radiator, such as potassium oxide and calcium oxide, for discharging electrons. The gas discharge tube contains argon, neon and krypton added with mercury, having its inner surface coated with fluorescent compositions. When a sufficient voltage is applied to the two ends of the tube, the filaments emit electrons colliding with mercury atoms at a gas discharging state to release ultraviolet rays having a wavelength of 253.7 nm. The ultraviolet rays excite the coated fluorescent composition to generate visible light, whose wavelength depends on its exact composition. Thus, visible light of various colors may be produced by various fluorescent compositions, including yttrium oxide blended with europium, phosphoric lanthanum terbium blended with cerium, and barium, aluminum magnesium oxide blended europium. It is estimated that 60 percent energy of inputting electricity is converted into ultraviolet rays, and only 40 percent energy of the ultraviolet rays is converted into visible light, wherein the rest of the energy is wasted in the form of heat. In other words, the illumination efficiency of fluorescent light is about 24 percent, about twice the efficiency of incandescent light. Although the fluorescent light is energy saving, it is fragile and contains polluting waste.
LED
An LED has many advantages over the traditional incandescent light, including compact, less hot, less energy consuming, longer living and less delaying. However the LED is very selective in terms of material choosing and crystal growth, so the manufacture is difficult. In addition, the voltage required for LED is different from the usual incandescent light and fluorescent light, so additional voltage conversion and AC to DC vonversion is reauired, increasing the cost of LED utilization for illumination purpose. Even so, in order to save energy and protect environment, many developed countries have adopted the LED as the standard lighting device for the twenty first century. Because many countries' energy supply relies on import, there is a great market potential for LED lights. According to estimation, if Japan replaces all its incandescent lights with LED lights, it will save energy consumption for the approximate amount generated by two power plants, which will indirectly reduce the consumption of fuel by one billion liters. As a result, the carbon dioxide released in the course of power generating will also be reduced, thereby alleviating the greenhouse effect.
The issue of building a nuclear power plant has invited heated arguments in Taiwan, and raises the need of discovering new energy and improving energy-using efficiency. If one fourth of the illumination apparatuses can save about thirty percent of energy in Taiwan, 11-billions-kilowatt-per-hour power will be saved, which is about a nuclear power plant's annual capability of power generating. As a result, the carbon dioxide released and fuel consumed for power generation will be reduced accordingly.
Thus, what is needed is an illumination apparatus that can improve the illumination efficiency of the traditional illumination devices in order to save energy without additional efforts for voltage conversion and AC to DC vonversion.